There are numerous instances where persons desire enlargement of the soft tissues in their bodies. One such instance is for the replacement of one or both breasts amputated during a mastectomy in order to restore physiological symmetry and psychological well-being. Other instances are for correction of natural abnormalities such as dimpling. Still other instances are for augmentation of physical attributes to improve cosmetics and self-esteem. These latter soft tissue enlargements are principally directed to breast enlargement in females and penis enlargement in males.
Prosthetic implants have been developed for insertion below the skin. However, the severity of the potential complications including scarring, implant rupture, capsular contracture, necrosis and implant migration as well as the recent adverse publicity thereof have significantly reduced the desirability of these implants. Thus, there is a societal need for other means to obtain soft tissue enlargement.
Some soft tissue enlargements occur naturally. For instance, during pregnancy, the skin over a woman's abdominal region enlarges approximately nine times its previous area to accommodate the fetus without a proportional decrease in skin thickness. In other words, the abdominal skin tissue actually enlarges and does not merely stretch during pregnancy. Similarly, the skin will expand to accommodate any growth under the skin.
In the past, plastic surgeons have used this phenomena to their advantage to expand skin in order to accommodate prosthetic implants. To conduct this procedure, the surgeon inserts a balloon beneath the skin in the area where additional skin is desired. By progressively expanding the balloon, the skin first stretches and eventually actually grows to accommodate the increased volume underneath it. When the desired amount of skin is formed, the balloon is deflated and removed, and the implant is inserted into the cavity left by the balloon. Similar methods have been used by native African tribes to enlarge lips, nostrils, and earlobes.
Other surgical techniques have used tissue expansion to achieve other types of soft tissue growth. For instance, balloons have been successfully expanded underneath nerves, veins, tendons, and the like to thereby elongate these tissues to repair damage and alleviate various abnormalities.
A more advanced surgical method is known as callotasis or limb lengthening. This method comprises cutting the bone about its periphery at the location where lengthening is desired, leaving the tissues inside and around the bone intact. Brackets are attached to the bone on each side of the separation, and the bone segments are slowly pulled away from one another while remaining integral over a period of several months. Not only does this cause the mended bone to be longer, but also the soft tissue surrounding the bone actually grows to accommodate the increased limb length. Similar methods have been used by African native tribes to lengthen necks for cosmetic purposes.
Each of these above-mentioned apparatuses and methods requires an invasive surgical technique to accomplish the soft tissue expansion. Invasive techniques increase the likelihood of the complications associated with the procedure including those mentioned above with respect to implant surgery. In addition, the expense of surgery precludes many persons having their abnormalities corrected or physical attributes enhanced.
Other soft tissue enlargement techniques have been developed which use other mechanisms to cause the enlargement. For instance, an instrument and technique have been developed for the non-surgical correction of inverted nipples due to short lactiferous ducts. The instrument is comprised of a cup having an internal volume shaped like that of the final desired nipple. The user places the cup over the inverted nipple, pumps the air out of the cup with a syringe and adjusts the vacuum within the cup using a check valve to just below the threshold of discomfort. Thus attached, the device puts the lactiferous ducts in tension and extends them sufficiently after two to three months of wear at 8-12 hours per day.
Although this device is sufficient for its intended purpose, it is not suitable for general soft tissue enlargement. Laceration and contusion can occur if too strong of a suction is applied to soft tissue. As the pressure within the inverted nipple instrument is not regulated, contusion or laceration can occur. When a vacuum is developed within the cup of the instrument, an equal and opposite force is applied to the patient about the rim of the cup. Excessive contact forces against the patient can cause ulceration, laceration, and contusions. As the contact forces are not regulated in the nipple instrument, these further complications also can occur. In addition, general soft tissue enlargement is not feasible with the instrument due to the size and shape of the cup.
Another prior art device is disclosed in U.S. Pat. No. 936,434 as a device for enlarging a woman's breasts. This device included a pair of cups for placement on the breasts and a pump for exhausting the air from between the cups and breasts. However, this patent provides no teaching as to the pressures to be used, the potential danger to the skin tissues, or any suggestions as to how the device is to be retained in place during use. Apparently, the device is used in a clinical setting and is not suitable for long term wear such as for 8-10 hours. As the patent suggests that the vacuum acts to cause the veins and arteries to engorge, thereby nourishing the breasts, it is clear that the patentee is suggesting that the breast tissue actually expands through this expansion of blood vessels alone. This patent has been the subject of ridicule by at least one medical authority. See "An Anthology of Plastic Surgery" edited by Harry Hayes, Jr., M.D., Section 6, "Quackery and Nostrums" pub. 1986 by Aspen Publishers, Rockville, Md.
Finally, another prior art device although notorious is worthy of note. This device is commonly referred to as a penis pump and is sold primarily as a novelty as its long-term enlargement efficacy has never been proven and is in fact universally disclaimed by its distributors. The device is comprised of a cylinder having one open end into which the penis is inserted and a pump attached to it such that a vacuum can be created within the cylinder. Not only does this device have the same drawbacks as the nipple instrument with respect to potential complications, but also it is unlikely that sufficient vacuum can be maintained by the device to cause any notable long-term soft tissue enlargement. Further, this device is apparently designed to accomplish two tasks unrelated to enlargement. First, the device is used for stimulation and sexual gratification. Second, the device is used to promote erection by drawing blood into the penis.
Most of these prior art devices and methods have failed to achieve long term soft tissue enlargement while preventing damage to the soft tissue being enlarged, as well as surrounding tissue. The inventor herein has succeeded in designing and developing a new generalized method and apparatus for soft tissue enlargement which prevents damage to soft tissue. The apparatus used for this enlargement is comprised of a variable volume dome which may be adhesively bonded to the skin adjacent the soft tissue and having a rim about its periphery. The rim has sufficient surface area such that the compressive stress applied to the patient by the rim and the tensile stress applied to the soft tissue under the dome are both applied at levels and for periods of time below which damage will not occur to the underlying soft tissue. In addition, a stress sensing device may be incorporated into the enlargement apparatus to assure that the compressive and tensile stresses are below predetermined limits where tissue damage would occur. As the previously mentioned pressure limits are ready converted to common units of stress or units of force, these limits may alternately be set in stress or force units.
In implementing the device of the present invention, the inventor intends that it be capable of achieving its therapeutic effect without creating any long term tissue necrosis from use. In other words, a tensile stress must be applied to the desired area to achieve the therapeutic effect for sufficient periods of time without applying too great a tensile or compressive stress which will damage the underlying tissue. As considered from this generalized approach, one of ordinary skill in the art would understand the inventor's teaching to include the idea of providing a smaller tensile stress caused by the enlarger and balancing that tensile stress with a rim having a surface area less than the normal area of the dome, thereby creating a greater compressive stress which is still within acceptable limits. Still another approach which may very well provide a therapeutic effect would be to cycle the tensile stress such that it is applied for periods of time at elevated levels and relaxed levels so that the rim might also have a cross-sectional area less than the normal area of the dome, but yet avoid creating any tissue necrosis. Therefore, the invention should be understood as being limited only by the current medical understanding of the causative effects of pressure sores and other tissue damage by an applied tensile or compressive stress.
It is well recognized in the medical literature that decubitus ulcers are caused by unrelieved external pressure or compressive stress that occludes blood flow and results in tissue necrosis. In recognition of this fact, these ulcers are called pressure sores. The average capillary pressure in human skin is around 15-20 mmHg. E. M. Landis, Micro-Injection Studies of Capillary Blood Pressure in Human Skin, 15 Heart 209-228, (1930). For convenience, 20 mmHg will be used to describe this pressure throughout the remainder of this description. However, it should be understood that pressures below 20 mmHg may also be used without departing from the scope of this invention and that these lower pressures may provide additional margins in preventing damage to tissues. Likewise, when an equivalent stress value is used, the equivalent range in stresses is also intended. Therefore, the local application of an external pressure up to 20 mmHg will not collapse capillaries adjacent the location of the applied pressure and thus will not disturb the circulation. Therefore, local application of contact pressures less than or equal to 20 mmHg are well tolerated for prolonged periods of time. This tolerance has been confirmed by the inventor through use of a prototype which did not cause adverse effects after many hours of continuous use as long as the pressure under the rim remained below or around 20 mmHg.
Pressures greater than 20 mmHg will occlude the capillaries and stop tissue perfusion. Tissues can tolerate short periods of ischemia, but if the pressure is continuous and perfusion is not restored within a relatively short period of time, tissue damage will ensue. "The time factor is thus more important than pressure intensity". A pressure of 100 mmHg will lead to pathologic changes after only two hours. T. Hussain, An Experimental Study of Some Pressure Effects on Tissues, with Reference to the Bed-Sore Problem, 66 J. Path. Bact. 347-358, (1953).
The experimental results of additional investigators can be used to develop a safe time-pressure curve above which tissue damage will ensue. For instance, 20 mmHg is well tolerated for prolonged periods of time, but 40 mmHg will lead to tissue injury if the pressure is not relieved for 13 hours. The injury is more severe if the pressure is 60 mmHg, and even greater injury will result with a pressure of 100 mmHg after shorter periods of time. O. Lindan, Etiology of Decubitus Ulcers: An Experimental Study, 42 Arch. Phys. Med. Rehab. 774-783, (1961). Similarly, a pressure of 70 mmHg, if unrelieved, will lead to pathologic changes after 2 hours. However, if the pressure is intermittent, applied 5 minutes on, and 5 minutes off, there is no pathologic tissue changes. M. Kosiak, Etiology of Decubitus Ulcers, 42 Arch. Phys. Med. Rehab. 19-29, (1961).
These findings are consistent with the clinical testing of the prototype of the breast device. It was found that a continuous pressure under the rim of 40 mmHg could be tolerated for only one hour by healthy volunteers. After one hour, the volunteers started to complain of pain which is the warning sign of impending tissue damage. Higher pressures led to pain under the rim after even shorter periods of tame. Lower pressures around 30 mmHg led to pain after 4 hours. However, if the pressure is allowed to cycle, that is if it is dropped down to 0-20 mmHg to allow the tissues to temporarily reperfuse for a few minutes, higher peak pressures can be tolerated. The higher the peak pressures, the shorter they are tolerated and the longer the low pressure part of the cycle needs to be to allow the tissues to recuperate. As will be readily appreciated by those of ordinary skill in the art, these pressure limits are easily converted to units of stress. Thus, rather than pressure limits, stress limits may be set. Likewise, as the relevant areas of interest may also be known, these stress limits may easily be converted to force limits by multiplying the particular stress limit by the appropriate known area measurement. Thus, limits may be set using any one of several measurement units depending upon scale desired.
Therefore, pressures under the rim greater than 20 mmHg can only be tolerated if there is a means to continuously cycle the pressure peaks on and off allowing for tissue re-perfusion during the off periods. The higher the peaks, the shorter the pressures are tolerated and the longer the period of low pressure recuperation needs to be.
From the above experimental animal data and human study, the inventor concludes that 20 mmHg is the highest pressure that can be safely tolerated under the rim on a prolonged basis. Higher pressures can only be applied intermittently, and then cycled down to less than 20 mmHg. As a pressure of 20 mmHg is equivalent to a stress of approximately 2666N/m.sup.2, the rim stress may be limited alternatively to this stress level instead.
The method of use is comprised of the steps of attaching the variable volume dome to the location of desired enlargement, and expanding the dome. In the continuous application method in which the stress is applied at levels that can be withstood continuously, the stress should be maintained for a minimum of eight hours per day and results should be sufficient after several months.
As indicated by the summary of the medical literature given above, the present invention may also be used in alternative methods in keeping within the scope of the inventor's concept. For example, the device might have a rim cross-sectional area substantially less than the normal area of the dome and be used in either of two methods. In a first method, a somewhat lower tensile stress may be induced in the dome such that the opposing compressive stress under the rim may be maintained at bearable levels for extended periods of time and yet provide a therapeutic effect. Alternatively, the vacuum tensile stress may be regulated in a routine which provides somewhat higher stresses for shortened periods of time separated by periods of lower stress to allow tissue reperfusion. In other words, alternating cycles of high stress, tissue reperfusion, high stress, tissue reperfusion, etc., may achieve a therapeutic effect in enlarging the soft tissues. With either of these methods, the rim may have a cross-sectional area substantially less than the normal area of the dome.
In implementing the present invention, the inventor has found that it is desirable to provide a gasket around the rim of the dome which has the ability to distribute the shearing forces generated between the skin and rim as the tensile stress is applied. In one embodiment, this is achieved by providing a rim made of silicone gel which has a thickness sufficient to allow its surface adjacent the skin to shift laterally with respect to the dome. In this way, the shearing stress is distributed along virtually the entirety of its contact surface and even beyond the periphery of the rim. Thus, the shearing stress is not concentrated as a high contact stress at the edge of the rim adjacent the pressurized area under the dome. As an alternative to a gel-like rim, the inventor has also considered the use of a balloon-like or inflated rim as specific embodiments of this aspect of the invention. Other configurations and constructions would be suitable, it only being desired to provide for a relative lateral shift between the dome and the surface of the rim which contacts the soft tissue as the tensile stress is applied to thereby distribute the shearing stress across the surface of the rim and beyond.
While the practical advantages and features of the present invention and method have been briefly described above, a greater understanding of the novel and unique features of the invention may be obtained by referring to the drawings and Detailed Description of the Preferred Embodiment which follow.